Semiconductor color image sensor devices have been used in video cameras, charge-coupled devices, and CMOS image sensors. Such image sensors are based on a two-dimensional array of pixels with each pixel including a color filter located over a sensing element. An array of microlenses located over the color filter focuses light from an optical image through the color filter into the image sensor elements. Each image sensing element (sensor) is capable of converting a portion of the optical image passing through the color filter into an electronic signal. The electronic signal from all the image sensing elements are then used to generate an optical image on a video monitor or other similar device.
FIG. 1 illustrates a prior art semiconductor color image sensor device 10. The device ten includes a semiconductor substrate 12, for example a silicon based substrate. A plurality of image sensing elements (sensors) are provided, for example a first sensor 4, a second sensor 6, and a third sensor 8. A first interlayer dielectric 16 is provided over the substrate 12. The first interlayer dielectric 16 may be any suitable dielectric known to those skilled in the art including doped silicon dioxide or glass. A first intermetal dielectric layer 18 is provided over the first interlayer dielectric 16. A second intermetal dielectric layer 20 is provided over the first intermetal dielectric layer 18. The first and second intermetal dielectric layers 18, 20 may be any dielectric material, for example, such as silicon dioxide. A plurality of air gaps 54 are formed through the first and second intermetal dielectric layers 18 and 20 and stop on the interlayer dielectric layer 16. A metallization layer 22 is provided over the second intermetal dielectric layer 20. A first passivation layer 24 covers the second intermetal dielectric layer 20 and the metallization layer 22. The first passivation layer 24 includes an upper surface 26 that is non-planar. The first passivation layer 24 may be silicon dioxide. A second passivation layer 28, such as silicon nitride, covers the first passivation layer 24. The second passivation layer 28 includes an upper surface 30 that is non-planar. A planarization layer 32 such as spin-on glass is formed over the second passivation layer 28 and has an upper surface 34 that is planar. The plurality of color filters such as a first color filter 36 which may be for example a red color filter, a second color filter 38 which may be for example a green color filter, and a third color filter 40 which may be for example a blue color filter overlie the planarization layer 32. A spacer layer 44 overlies the color filters 36, 38, 40. A plurality of microlenses 46 are formed over the spacer layer 44 with one microlens 46 being aligned with one of the color filters 36, 38, or 40. As will be appreciated from the light rays 48, 50 and 52, the color image sensor device operates such that a first light ray 48 may enter through one of the microlenses 46 overlying the second color filter 38, travel through the second color filter 38 and may be reflected by one of the first or second intermetal dielectric layers 18 or 20 at the interface with the air gap 54 so that the light ray 48 eventually strikes sensor element 6 which is aligned with the color filter 38. However, as shown by light rays 50 and 52, light may enter through the microlens 46 vertically aligned with the second color filter 38 but travel through the various layers of the device and not strike the second sensing element 6. The light rays 50 and 52 may strike another sensing element, such as sensor 8. This type of light scattering produces cross talk that is unwarranted.
In prior color image sensor devices, the color filters 36, 38, and 40 are arranged to have an overlap region 42 wherein an adjacent color filter, for example 38, overlaps a portion of an adjacent color filter, for example 40. FIG. 2 is a plan view of a portion of a prior art semiconductor device including an image sensor element illustrating the overlap region 42 of adjacent color filters.
The present invention provides alternatives to the prior art.